1. Field of the Invention
The present invention relates to an apparatus and a method for inspecting a defect in an object surface, in which a foreign matter existing in a thin film substrate, a semiconductor substrate, and a photomask or the defect generated in a circuit pattern is detected in producing a semiconductor chip or a liquid crystal product.
2. Description of the Related Art
In a semiconductor production process, existence of the foreign matter on the semiconductor substrate (wafer) causes an insulation failure or a short circuit of an interconnection. As a process of a semiconductor element is moved to a finer design rule, a finer foreign matter causes an insulation failure of a capacitor or a breakage of a gate oxide film or the like. The foreign matters are generated in various states from various factors such as a moving part of a conveyance apparatus, a human body, reaction of a process gas in a treatment apparatus, and an impurity of a chemical or a material.
Similarly, in a liquid crystal display element production process, the liquid crystal display element is spoiled when a pattern defect is generated by the foreign matter. Similarly, in the printed circuit board production process, the mixing of foreign matter causes the short circuit and connection failure of the pattern.
Therefore, in the semiconductor production, a foreign matter inspection apparatus or a plurality of foreign matter inspection apparatuses in some cases is disposed in each production line, and early detection of the foreign matter is fed back to the production process to enhance a yield of the semiconductor production.
For example, Japanese Patent Application Laid-Open (JP-A) No. 62-89336 discloses a technique of detecting the foreign matter on the semiconductor substrate, wherein the semiconductor substrate is irradiated with a laser beam to detect scattered light which is generated in the case where the foreign matter adheres onto the semiconductor substrate, and the scattered light is compared to that of the inspection result of the same type semiconductor substrate inspected immediately before, whereby the foreign matter and defect can be inspected with high sensitivity and high reliability while misinformation is eliminated.
JP-A No. 2001-60607 discloses a technique of measuring a foreign matter size.
Because high-speed and high-sensitivity inspection is demanded in the foreign matter inspection apparatus, speed enhancement of a wafer moving stage, high NA and high resolution of a detection optical system becomes significant in development on the inspection apparatus. It is also necessary to prevent not only the generation of dust from the inspection apparatus per se but also adhesion of the new foreign matter to an inspection target during the inspection.
However, even if cleanness in the inspection apparatus is improved to prevent the generation of dust, because of the existence of the moving part such as the conveyance unit, it is substantially difficult to make an expensive atmosphere in which the foreign matter is completely removed.
In the technique disclosed in JP-A No. 62-89336, the micro foreign matter or defect on the substrate in which a repetitive pattern and a non-repetitive pattern coexist cannot easily be detected with high sensitivity and at a high speed. That is, there is a problem in that detection sensitivity (minimum detectable foreign matter size) is lowered in portions except for the repetitive pattern portion such as a memory cell portion.
Additionally, in the technique disclosed in JP-A No. 62-89336, there is a problem in that the detection sensitivity is lowered for the micro foreign matter or defect having a level of 0.1 μm in an area where pattern density is high.
Additionally, in the technique disclosed in JP-A No. 62-89336, there is a problem in that the detection sensitivity is lowered for a thin-film-like foreign matter or the foreign matter and defect which cause the short circuit between interconnections.
In the technique disclosed in JP-A No. 2001-60607, there is a problem in that measurement accuracy is lowered for the foreign matter or defect. Additionally, there is a problem in that the detection sensitivity is lowered for the foreign matter on a wafer surface in which a transparent thin film is formed.
An object of the invention is to realize the defect inspection method and apparatus being able to accurately inspect the micro foreign matter or defect at a high speed for the inspection target substrate in which the repetitive pattern and the non-repetitive pattern are mixed.